Appropriate Technology

Like many of you, I suspect, we’ve got a few too many tomatoes at this time of the year. One of our favorite ways to preserve our modest harvest is with our solar dehydrator. There’s nothing like the taste of sun dried tomatoes, but unless you live in a very dry desert climate like Phoenix, Arizona you can’t just set fruit out in the sun and expect it to do anything but go moldy. In most places in the world, including here in Los Angeles, the relative humidity is too high to dry things out in the sun. Solar dehydrators work by increasing air flow to dry out the food. The one we built uses a clever strategy to get air moving without the use of electric fans such as you’d find in your typical store bought electric dehydrator.

Our solar dehydrator is constructed out of plywood and consists of a heat collector containing a black metal screen housed in a box with a clear plastic top. This screen heats up on a sunny day and feeds hot air into a wooden box above it. Vents at the bottom and the top of the contraption create an upward airflow through natural convection (hot air rises). You put the food on screen covered trays in the upper box. With sliced tomatoes it takes about two full days of drying and you have to take the food indoors at night to prevent mold from growing (a minor inconvenience). We built our dehydrator several years ago and have used it each season for tomatoes, figs and for making dried zucchini chips.

You can find plans for this “Appalachian Dehydrator”, designed by Appalachian State University’s Appropriate Technology Program, in the February/March 1997 issue of Home Power Magazine. The February/March 1999 issue of Home Power features a refinement of this plan, but we just built the original design and it works fine. The original plans and improvements to those plans are split between two articles: Issue #57 and Issue #69. You need to download and read through both before building this dehydrator. . Alternatively, the always excellent Build it Solar website has a whole bunch of solar dehydrator designs, including a nice cardboard version. And while you’re in the library there’s also a book by Eben Fodor, The Solar Food Dryer.

As an added bonus to the tinkerers out there, take almost any of these designs, remove the top box, stick it in a window and you’ve got a passive solar room heater.

Our rocket stove, pictured above, was mentioned on BoingBoing last week and we thought we’d use the occasion for a brief roundup of similar “appropriate” technology concepts. The term appropriate technology evolved out of political economist E. F. Schumacher’s book Small is Beautiful and is easier to show rather than describe. While not always low-tech, appropriate tech concepts feature elegantly simple (but not simplistic) design, efficient use of energy and are usually aimed at poor countries. What Homegrown Evolution would like to prove is that these technologies have a place in developed western countries as well. Here’s three of our favorite appropriate tech ideas and websites:

Root Simple dropped by Houston’s famous Beer Can House, created by John Milkovisch in the 1960s and 70s. We won’t plumb the messy depths of the meaning of “visionary art”, the academic art Mafia’s euphemism du jour for this stuff–we’ll leave that to our art bloggin’ amigo Doug Harvey.

So sidestepping the whole debate over the intentions of its creator, we’ll point out that all of Milkovisch’s house mods have both aesthetic and practical benefits. The beer can cladding that covers the entire exterior of the house means never having to paint the underlying wood. The concrete yard means never having to mow a lawn (we’d prefer vegetation but Milkovisch’s concrete work is, like the rest of the house, magical).

But on to our favorite detail. It’s damn hot in Houston most of the year, and to deal with the blazing sun on the south side of his humble bungalow, Milkovisch crafted this intricate, shimmering screen made of beer can tops and bottoms that hangs from the roof line like an aluminum grass skirt. Not only does it shade the windows and walls, producing a dramatic decrease in cooling bills, but it also functions as a pleasing wind chime.

We’ve been thinking of doing something similar on the hot south side of our house, except with deciduous vines. That way, we’ll let light in during the winter and have a living shade wall during the summer. Perhaps we’ll grow beans and become Los Angeles’ Bean House.

Root Simple is about back to basics, DIY living, encompassing homegrown vegetables, chickens, herbs, hooch, bicycles, cultural alchemy, and common sense. We’re always learning, figuring stuff out, taking advantage of the enormous smarts of our friends and our on-line community, and trying to give some of that back in turn. Root Simple is a gathering place for everyone. Welcome.

Root Simple is about back to basics, DIY living, encompassing homegrown vegetables, chickens, herbs, hooch, bicycles, cultural alchemy, and common sense. We’re always learning, figuring stuff out, taking advantage of the enormous smarts of our friends and our on-line community, and trying to give some of that back in turn. Root Simple is a gathering place for everyone. Welcome.